1. Field of the Invention
The present invention relates to a camera body on which an image pickup lens unit that includes a photographing optical system and an image pickup element is detachably mounted, and a camera system including the camera body and an image pickup lens unit.
2. Description of the Related Art
Conventionally, in the field of a silver salt camera, there is known a camera system of a lens detachable type with a photographing lens detachably mounted on a camera body.
In recent years, in the field of a digital camera, a digital camera of a lens unit detachable type has been proposed as in the field of a silver salt camera. For example, Japanese Patent Application Laid-Open No. 8-172561 (pages 2 to 4, FIG. 1) discloses a camera system that includes a lens unit, in which an image pickup element and an optical system are maintained in a predetermined positional relation, and a camera body, to which the lens unit is connected, and facilitates replacement of the lens unit.
In addition, for example, Japanese Patent Application Laid-Open No. 2000-175089 (pages 2 to 4, FIG. 1) discloses a camera system that includes: an interchangeable lens unit having a photographing lens, an image pickup element, and storing means, which receives a control program from a camera body and stores the control program; and a camera body having processing means, which subjects an image signal from the image pickup element to signal processing and then records the image signal in a recording medium, and a central processing unit, which controls the processing means on the basis of the control program received from the storing means. The interchangeable lens unit is detachably mounted on the camera body.
In recent years, in accordance with advances in a liquid crystal display apparatus and various communication device techniques, it has become possible to give a camera not only the photographing function and the recording function described above but also a reproducing function for reproducing image information obtained by photographing, a communication function for transmitting and receiving image information to and from other apparatuses, or the like. A digital camera having such plural functions is widely spread.
However, when the plural functions are given to the camera as described above, various problems occur from the viewpoint of operability of the camera. For example, in the conventional digital camera, since precision elements such as the photographing optical system and the image pickup element are always incorporated in the camera main body, a user has to operate the digital camera carefully such that a shock is not applied to the digital camera.
In addition, since photographing operation of a camera is usually performed in a state in which the camera is retained in a horizontal position, as a premise, the user also operates the camera with both hands at the time of reproduction of image information. This is often inconvenient because the user uses both hands while moving and the like, and thus operability of the camera falls.
Further, it is possible to improve the photographing function by adopting a camera system including an image pickup lens unit, in which a photographing optical system and an image pickup element are integrated, and making the image pickup lens unit replaceable. However, there is a problem in that it is hard to use the camera system when operability for the reproduction function, the communication function, and the like is still low.
Japanese Patent Application Laid-Open No. 8-172561 and Japanese Patent Application Laid-Open No. 2000-175089 disclose the invention concerning the photographing function and the recording function but do not refer to operability of the entire camera system including the reproduction function, the communication function and the like.